The Colors and Varieties of Garnet The Colors and Varieties of Garnet The Colors and Varieties of Garnet Published: May 2010 by Cara Williams, F.G.A Garnets are not just a family. They are more like a clan. They have much in common – the same crystal form (cubic) and the same chemical outline. I say outline, because in many ways, chemistry varies between the different types of garnets. So while we call them a family, their DNA varies enough to call them a clan. Gemologists recognize six garnet families within the garnet clan. Five are well known: pyrope, almandine, spessartite, grossular, and andradite. The sixth, uvarovite, is hardly ever seen or heard from. (If you didn’t catch the name of your favorite, hold on – we will get to it in part 2 of this report.) Besides these six gem garnets, mineralogists know about more than 30 others, some just theoretical. Yes, there is a lot we didn’t know about that January birthstone. Read more about garnet in our Gemopedia™ Garnets adhere to a three-part formula.

There is a silicate component, as well as two other elements. The ratio of these components does not vary. (For more detail, please look at the chart below.) The six garnet families tend to hang out in two groups – an aluminum group and a calcium group. They occasionally mix – or intermarry – but not much. Aluminum, calcium, and silicate do not cause color; the other elements do – those wild “genes.” The aluminum garnets are called pyralspites, a word formed from the individual names pyrope, almandine, and spessartite. The calcium garnets are ugrandites - uvarovite, grossular, and andradite. Now imagine the garnets as a very old, established clan. While individuals might have a certain last name, they are not just a Jones or a Smith. They are a combination of whatever their ancestors were. So we never have a pure pyrope or a pure almandine. Pyralspites Pure pyrope would be colorless, but we all know there are no colorless garnets.

Pyropes are always red, getting their color from some almandine ancestry and sometimes from a bit of uvarovite. (Bits of uvarovite “genes,” or molecules, pop up in many garnets’ DNA.) Almandine is the classic red garnet and possibly the most common type. It has iron in its formula, which creates color - in this case, a strong red. This is why it does not take much almandine in a garnet to make it red. Spessartite is the third pyralspite, and it has manganese in its formula. This manganese creates a yellowish-orange color. Because many of spessartite’s ancestors married almandines, many are a reddish orange due to some iron. The lighter orange spessartites, similar in color to orange soft drinks, are almost pure spessartites. Ugrandites The other group of gem garnets, the ugrandites, is not as well known or as plentiful as the pyralspites. Uvarovite, a rich, emerald green, has chromium in its formula, which stunts crystal growth.

This garnet is rarely seen as anything other than a drusy (lots of tiny crystals all close together); however, it leaves its mark on other garnets more than you might think. Grossular garnet has aluminum and calcium in its formula, neither of which creates color. However, grossulars can range widely in their shades and are often close to pure. They get their color from traces of other garnets mixed in. Andradite is the last garnet and is different from the others in several ways. It has iron, but in a different state and position within the structure than almandine. Therefore, it does not create red. Instead, andradites can be golden or brown or even other colors if mixed. Garnet Varieties: Part 2 I suspect many of the garnet names we covered in Part 1 may be new to some. That is because the various garnets are usually called by trade names that were created as different finds were discovered. Because no garnet is pure and many are composed of combinations of three or more garnets, it is too confusing to stick to the gemological names.

So, we have always named these varieties on their appearance, gemological properties, and origin - regardless of what the actual chemistry is. The best-known garnet mix is rhodolite, a pinkish or purplish garnet. It generally is about half almandine and half pyrope, usually with a few minor amounts of other garnets mixed in. It is more of a color name. Malaya garnets are a combination of all three pyralspites, usually in nearly equal amounts. The word Malaya, also spelled Malaia, comes from the Swahili word for “no family” because it belongs to no major garnet family. It is a combination of many. Pink garnets are mostly pyropes - and about as pure as pyropes come. As pure pyropes are colorless, the small almandine component creates a lighter red, hence the pink. Garnets that are colored by iron have a very different red look than chromium-colored rubies or spinels. However, there are unusual red garnets that are colored by chromium. These are anthill garnets, only found in small sizes but with a big color – a pure, deep red.

Anthills are mostly pyrope, and they get their name from how they were discovered. The small crystals would be found mixed in desert sands in Arizona. The ants would bring them to the surface when building nests because they did not want these hard little rocks in their beds. We are so grateful they did! Color-change garnets are mostly a combination of spessartite and pyrope, usually with a very small amount of one of the rare garnets mixed in. Their colors can vary, depending on the light and the particular stone, but they range from green to red to golden to brown to purple to sometimes blue. They are an interesting study in themselves – possibly in need of a gem therapist! Mozambique garnet, Tanga garnet, and Umbalite garnet, which have a common look and color, are mixed stones from the particular areas they are named for,. They are part of the clan but close to no one family. Names like mandarin garnet or rhodolite garnet signify a particular color or color range. The ugrandite garnets are typically more pure and tend to not be as varied as the pyralspites. However, they still have wide variations in color.

Tsavorite is probably one of the most beautiful gems. It is a grossular garnet colored by vanadium and sometimes chromium, as well. The vanadium comes from one of the rare garnets (it only takes a small amount), while the chromium probably comes from some uvarovite. Tsavorites can be an intense, deep green, but if too light, they become mint garnet. Hessonite, another type of grossular, is typically a brownish orange and gets its color from iron. Grossular can range into some beautiful golden colors, as well, such as imperial. The andradite garnets can be green (demantoid) to yellow (topazolite) to brown. Demantoid, one of the rarest and most valuable garnets, is andradite colored green by chromium - likely uvarovite again. There are also Mali garnets, one of the more recent additions, discovered in Mali, Africa. These are a combination of grossular and andradite and can range from green to brown in color. Much like their components, their color is caused by chromium and/or iron. So the garnets are a unique clan among gems.

Their chemistry varies, yet remains similar – similar enough for them to continue to mix in varying degrees. Few gems offer the variety of colors and looks that garnets do. There is something for every taste and budget! Editor’s Notes: Our guest author, Cara Williams, is a highly respected gemologist with a long history in the field. Cara, who works for Stone Group Laboratories, has earned the advanced gemological degree, F.G.A. (Fellow of the Gemmological Association in Great Britain). Related Articles Garnet: The gemstone Garnet information and pictures Garnet ON EBAY ALL ABOUT Almandine and Pyrope are the most widely used Garnet gemstones. Though Almandine is the most common Garnet, it is usually opaque and not fit for gemstone use. Only the less common transparent dark red forms of Almandine are used as gemstones. Pyrope is especially noted for its transparency and frequent lack of flaw s or inclusion s. A rose-red to violet variety of Pyrope (or intermediary between Almandine and Pyrope) is known as Rhodolite , and is a very well represented in the gem trade.

Spessartite is an orange to orange-red form of Garnet, and has recently increased in popularity, with several new deposits of gem grade material having been recently exploited. Grossular , the most varicolored form of Garnet, has the important gem variety of green Tsavorite , as well as orange-brown Hessonite and a yellow to yellow-green form. Andradite , the most lustrous of the Garnets, has the rare green Demantoid variety, the yellow Topazolite variety, and the black Melanite variety. Uvarovite , the rarest of the familiar garnets, is seldom found in crystals large enough to be faceted, and is the least represented of all the familiar Garnets. Color-changing Garnet is an interesting form of this gemstone that has a different color when viewed in natural and incandescent lighting. It can have several color combinations, especially brown or orange in daylight to a pink or light red in incandescent light. Garnets occasionally displays asterism in the form of four-rayed stars. However, Star Garnets are very rare, and generally occur in opaque stones with only a weak asterism effect; thus interest in Star Garnets are limited.

USES Garnet is a very popular gemstone, and is the most well-known dark red gemstone. Red Garnet gemstones ( Almandine and Pyrope ) are very affordable and faceted into all types of jewerly, including necklaces, rings, bracelets, and earrings. Round cabochon s of red Garnet are also popular and used in rings and bracelets. The variety Rhodolite has become a very important jewelry gemstone, and the rare green Tsavorite and Demantoid Garnets make exquisite and costly gemstones. Color Changing Garnet has sparked recent interest, and it is most often used in rings. Other forms of Garnets such as orange Spessartite , yellow Grossular and black Melanite are also used as gemstones. Garnet is the birthstone for January. Garnet TREATMENTS AND ENHANCEMENTS Garnet gemstones are not enhanced, and their colors are always natural. Treatments such as heat treatment and irradiation have proved ineffective upon the Garnet gemstones. Several synthetic Garnets are simulants of other gemstones.

The most widely known synthetic Garnet is Yttrium Aluminium Garnet (YAG), Y3Al2(AlO4)3, and it is a colorless simulant of Diamond . Widely used until the 1970's, YAG has lost its stake Cubic Zirconia as a Diamond simulant. Gadolinium Gallium Garnet (GGG), Gd3Ga2(GaO4)3 is another synthetic Garnet form. It is rarely used as a gemstone though, and is most often produced for industrial and optical uses. Garnet- doublet s are made of a colored glass bottom with a Garnet gemstone fused to the top of the stone. Garnet doublets are rarely created anymore due to the affordability of Garnet gemstones. Garnet: a mineral, a gem, an abrasive, a filter and more! 6.5 - 7 green The compositions listed above are for end members of several solid solution series. There are a number of other garnet minerals that are less frequently encountered and not as important in industrial use.

They include goldmanite, kimzeyite, morimotoite, schorlomite, hydrogrossular, hibschite, katoite, knorringite, majorite, and calderite. As seen above, there are a variety of different types of garnet, and each has a different chemical composition. There are also solid solution series between most of the garnet minerals. This wide variation in chemistry determines many of their physical properties. As an example, the calcium garnets generally have a lower specific gravity, a lower hardness and are typically green in color. In contrast, the iron and manganese garnets have a higher specific gravity, a greater hardness and are typically red in color. Almandine garnet: Excellent cubic crystals of almandine garnet in a fine-grained mica schist from Granatenkogel Mountain, Austria. Specimen and photo by Arkenstone / . Andradite garnet: Green andradite garnet of the demantoid variety on a matrix of marble. This specimen is about 8.9 x 6.5 x 4.8 centimeters in size and was collected in Antsiranana Province, Madagascar.

Garnets formed within marble often have excellent crystal form and are of very high quality. Specimen and photo by Arkenstone / . Garnet gneiss: A coarse-grained gneiss composed mainly of hornblende (black), plagioclase (white) and garnet (red) from Norway. Public domain photo by Woudloper. Alluvial garnet crystals: These almandine-spessartine garnets are from an alluvial deposit in Idaho. They have been transported a short distance from their source rock, and some still retain evidence of their dodecahedral crystal form. They are about four to five millimeters in size and weigh about 0.6 to 0.8 carats each. How Does Garnet Form? Garnet in Metamorphic Rocks Most garnet forms at convergent plate boundaries where shale is being acted upon by regional metamorphism . The heat and pressure of metamorphism breaks chemical bonds and causes minerals to recrystallize into structures that are stable under the new temperature-pressure environment. The aluminum garnet, almandine, generally forms in this environment.

As these rocks are metamorphosed, the garnets start as tiny grains and enlarge slowly over time as metamorphism progresses. As they grow, they displace, replace, and include the surrounding rock materials. The photo below shows a microscopic view of a garnet grain that has grown within a schist matrix. It included a number of the host rock's mineral grains as it grew. This explains why so many garnets formed by regional metamorphism are highly included. Garnet mica schist in thin section: This is a microscopic view of a garnet grain that has grown in schist. The large black grain is the garnet, the red elongate grains are mica flakes. The black, gray, and white grains are mostly silt or smaller size grains of quartz and feldspar. The garnet has grown by replacing, displacing, and including the mineral grains of the surrounding rock. You can see many of these grains as inclusions within the garnet. From this photo it is easy to understand why clean, gem-quality garnets with no inclusions are very hard to find. It is also hard to understand how garnet can grow into nice euhedral crystals under these conditions.

Photo by Jackdann88, used here under a Creative Commons license . The calcium garnets typically form when argillaceous limestone is altered into marble by contact metamorphism along the edges of igneous intrusions. These are andradite, grossular, and uvarovite, the slightly softer, typically green garnets with a lower specific gravity. Two calcium garnets are highly regarded in the gem trade; they are tsavorite (a bright green grossular) and demantoid (a golden-green andradite). Garnet in Igneous Rocks Garnet often occurs as an accessory mineral in igneous rocks such as granite . Many people are familiar with almandine garnet because it is sometimes seen as dark red crystals in the igneous rocks used as granite countertops. Spessartine is an orange garnet found as crystals in granite pegmatites . Pyrope is a red garnet that is brought to Earth's surface in pieces of peridotite that were torn from the mantle during deep-source volcanic eruptions. Garnet is also found in basaltic lava flows. Garnet in Sedimentary Rocks and Sediments Garnets are relatively durable minerals.

They are often found concentrated in the soils and sediments that form when garnet-bearing rocks are weathered and eroded. These alluvial garnets are often the target of mining operations because they are easy to mine and remove from the sediment/soil by mechanical processing. Uses of Garnet Garnet has been used as a gemstone for thousands of years. In the past 150 years, it has seen many additional uses as an industrial mineral. The chart below shows recent industrial uses of garnet in the United States. Garnet is also used as an indicator mineral during mineral exploration and geologic assessments. Uses of Garnet: This chart shows the most common industrial uses of garnet minerals. Almandine is the variety of garnet that is most often used in industry. Garnet abrasive: This photo shows garnet granules that have been crushed and size-graded for use as abrasive, cutting, and filter media. They are used in waterjet cutting, "sand" blasting, sandpaper, water filtration, and a number of other uses. Almandine is the hardest garnet and also the most abundant. It is the garnet of choice for most abrasive applications. Photo by the United States Geological Survey.

Garnet crystal: Almandine, a variety of garnet from River Valley, Ontario, Canada. This specimen is a nice euhedral crystal approximately 2 inches (5 centimeters) across. These types of crystals are often weathered out of a garnet-bearing mica schist and are transported by streams. Almandine garnet: Almandine, a variety of garnet from Lount Township, Ontario, Canada. This is a granular specimen approximately 11.4 centimeters across. Garnet as an Industrial Mineral Garnet Abrasives The first industrial use of garnet was as an abrasive. Garnet is a relatively hard mineral with a hardness that ranges between 6.5 and 7.5 on the Mohs Scale . That allows it to be used as an effective abrasive in many types of manufacturing. When crushed, it breaks into angular pieces that provide sharp edges for cutting and sanding. Small granules of uniform size are bonded to paper to produce a reddish color sandpaper that is widely used in woodworking shops. Garnet is also crushed, screened to specific sizes, and sold as abrasive granules and powders.

In the United States, New York and Idaho have been important sources of industrial garnet for abrasives. Waterjet Cutting The largest industrial use of garnet in the United States is in waterjet cutting. A machine known as a waterjet cutter produces a high-pressure jet of water with entrained abrasive granules. When these are directed at a piece of metal, ceramic, or stone, a cutting action can occur that produces very little dust and cuts at a low temperature. Waterjet cutters are used in manufacturing and mining. Abrasive Blasting Garnet granules are also used in abrasive blasting (commonly known as "sand blasting"). In these processes, a tool propels a stream of abrasive granules (also known as "media") against a surface using a highly pressurized fluid (usually air or water) as a propellant. Abrasive blasting is done in order to smooth, clean, or remove oxidation products from metals, brick, stone, and other materials. It is usually much faster than sanding by hand or with a sanding machine. It can clean small and intricate surfaces that other cleaning methods would miss. Abrasives of various hardnesses can be used to clean a surface of greater hardness, without damaging the surface.

Filtration Garnet granules are often used as a filter media. Small garnet particles are used to fill a container through which a liquid flows. The pore spaces of the garnet are small enough to allow passage of the liquid but are too small to allow passage of some contaminant particles, which are filtered from the flow. Garnet is suited for this use because it is relatively inert and has a relatively high specific gravity. Garnet granules, crushed and graded to about 0.3 millimeters in size, can be used to filter out contaminant particles as small as a few microns in diameter. Garnet's high specific gravity and high hardness reduce bed expansion and particle abrasion during backflushing. Garnet peridotite: Garnet peridotite from Alpe Arami, near Bellinzona, Switzerland. The material in this rock originated within Earth's mantle and was delivered to the surface through a volcanic pipe during a deep-source volcanic eruption . The garnets are the reddish purple grains within the rock. Garnets weathered from such pipes often serve as indicator minerals when exploring for volcanic pipes that might contain diamond . Public domain photo by Woudloper.

The best way to learn about minerals is to study with a collection of small specimens that you can handle, examine, and observe their properties. Inexpensive mineral collections are available in the Geology.com Store . Garnet as a Geological Indicator Mineral Although most of the garnets found at Earth's surface have formed within the crust, some garnets are brought up from the mantle during deep-source volcanic eruptions. These eruptions entrain pieces of mantle rock known as "xenoliths" and deliver them to the surface in a structure known as a "pipe." These xenoliths are the source of most diamonds found at or near Earth's surface. Diamond pipe: Simplified cross-section of a diamond pipe and residual soil deposit showing the relationships of xenoliths and diamonds with the pipe and residual soil. Although xenoliths contain diamonds, they often contain a tremendous number of garnets for every diamond, and those garnets are generally larger in size. These deep-source garnets are very different from the garnets that form in the crust at shallow depth. So, a good way to prospect for diamonds is to look for these unique garnets. The garnets serve as "indicator minerals" for geologists exploring for diamond deposits.

As the xenoliths weather, their garnets are liberated in large numbers. These unusual garnets then move downslope in soils and streams. Geologists who find them can follow the garnet trail to the source deposit. Some of the diamond pipes in Canada were found by following a garnet trail produced by moving ice. African garnets: African garnets of various colors: orange spessartine (Mozambique), yellow mali (Mali), red almandine (Madagascar), green tsavorite (Tanzania), and purple rhodolite (Mozambique). In the past two decades, Africa has become a major source of excellent beautiful garnets with great color and clarity. Melanite garnet: Melanite is an opaque black garnet that is unusual to find in jewelry today. Along with jet, black chalcedony, and other black gems, melanite was often used in jewelry during the Victorian Era. These two rose-cut melanite rounds are about 9 millimeters across. Garnets as Gemstones Garnet has been used as a gemstone for over 5000 years.

It has been found in the jewelry of many Egyptian burials and was the most popular gemstone of Ancient Rome. It is a beautiful gem that is usually sold without treatment of any kind. It is also durable and common enough that it can be used in jewelry at a relatively low cost. Garnet continues as a popular gemstone today. It serves as a birthstone for the month of January and is a traditional gem given on a second anniversary. Most people will think of a red gemstone when they hear the name "garnet" because they are not aware that garnet occurs in a variety of colors. However, gem-quality garnets occur in every color - with red being the most common and blue garnets being especially rare. Red almandine is the red garnet most often found in jewelry because it is abundant and inexpensive. Pyrope and spessartine are reddish garnets that are commonly encountered in jewelry for the same reason. In recent decades, green demantoid garnet has become popular. It has a dispersion of 0.057 that gives it a "fire" which exceeds that of diamond's at 0.044.

Green tsavorite has a bright, rich color that is very much like emerald . It is commonly used as an alternative stone to emerald. Both of these green garnets are becoming more popular, but their price is much higher than almandine. Rhodolite garnet: Rhodolite, a variety of garnet, in mica schist from Jackson County, North Carolina. Specimen is approximately 8.9 centimeters across. Andradite Garnet: Andradite, a variety of garnet, massive with wollastonite from Willsboro, New York. Specimen is approximately 6.4 centimeters across. Garnet Information [1] Gemstones of the World : Walter Schumann; Sterling Publishing; fifth edition; 320 pages; 2013. [2] Garnet -- An Essential Industrial Mineral and January's Birthstone: James G. Evans, Phillip R. Moyle, David G. Frank and Donald W. Olson; United States Geological Survey Fact Sheet 2006-3149; 2006. [3] Industrial Garnet : Donald W.

Olson; United States Geological Survey Minerals Yearbook, 2012. [4] Industrial Garnet : Donald W. Olson; United States Geological Survey Mineral Commodity Summary, 2014. More Minerals Varieties of Garnet Stone Zircon Varieties of Garnet Stone Garnets are historically one of the most important of the colored gemstones, valued for their good hardness and excellent brilliance. The name garnet actually refers to a family of different gemstones. There are many different varieties of garnet, but no gemstone that is simply called "garnet". All of the different garnets share a common crystal structure but vary in their chemical composition. Gemology recognizes six common species of garnet based on their different chemical composition. They are pyrope, almandine, spessartite, grossularite, uvarovite and andradite. In addition to these six species, there are a number of other garnet varieties that are distinguished in the gem trade, based on their color or other special properties. Altogether there are at least 17 different varieties of garnet. Iron aluminum silicate, typically red with a violet tint.

Andradite Garnet Calcium iron silicate, the andradite group includes demantoid, melanite and topazolite. Color-Change Garnet A mix of spessartite and pyrope garnet. This rare garnet presents a color change from brownish or orange in daylight, to rose-pink in incandescent light. Demantoid Garnet A type of andradite garnet that is the most valuable of all the garnets, due to its outstanding luster and dispersion. Grossularite (or Grossular) Garnet Calcium aluminum silicate, the grossular group includes grossularite, hessonite, leuco, hydrogrossular and tsavorite garnet. Hessonite Garnet A type of grossular garnet that is often called cinnamon stone for its brownish-red color. Hydrogrossular Garnet A type of grossular green garnet that is dense and opaque, resembling jade. Leuco Garnet A type of grossular garnet that is entirely colorless. Mali Garnet One of the hybrid garnets, Mali is a mixture of grossular and andradite garnet. It is green in color with excellent luster and dispersion.

Melanite Garnet An opaque black variety of andradite garnet. Pyrope Garnet Magnesium aluminum silicate, typically red with a brownish tint. Rhodolite Garnet One of the hybrid garnets, rhodolite is a mixture of pyrope and almandite garnet. Colors range from ruby-red to purple. Spessartite (or Spessartine) Garnet Magnesium aluminum silicate, typically mandarin-orange to orange-red. Star Garnet Garnets that display asterism (the star affect) are rare and have so far been found only in two places in the world (Idaho, USA and India). Topazolite Garnet A type of andradite garnet that is yellow to lemon-yellow in color. Its similarity to yellow topaz is the reason for its name. Tsavorite Garnet A type of grossular garnet colored by chrome, resulting in a bright-green to emerald-green color. The second most valuable of all the garnets. Uvarovite Garnet Calcium chromium silicate, typically emerald-green. It is rarely found in gemstone quality.

First Published: July-19-2010 Last Updated: July-17-2014 © 2005-2016 GemSelect.com all rights reserved. Reproduction (text or graphics) without the express written consent of GemSelect.com (SETT Company Ltd.) is strictly prohibited. See more related information below Garnets Garnets People love garnets because of their colors and shape. The most common color is deep red, but they also come in black, green, cream, and other colors. Perfect garnet crystals have 12 diamond-shaped sides. Clear (but colored) garnets are used in jewelry, but garnets more commonly contain tiny inclusions that make them opaque and 'dirty' looking. The unusual hardness of garnets (H ~ 7) makes non-jewelry garnets great in sandpaper. The largest garnet here is over an inch across. The cream-colored garnet has a perfect crystal form. The bottom and right garnets also show the diamond-shaped faces, while the top garnet is just irregularly round. The 'dirty' garnet on the right has many inclusions. These deep red garnets are roughly the size of BBs.

Their shapes are round but irregular. This photo looks good blown up. Click on the photo for a full-sized image. These garnets are roughly the size of the tiny pellets used in bird shot (< 1 mm). If you zoom in on these, you will see that many show the diamond faces of the perfect 12-sided garnet. By the way, a 12-sided figure is called a dodecahedron. This close up of garnets roughly 5 mm across shows that garnets have no cleavages, just irregular fractures. The greenish streaks running up and down from each garnet are chlorite pressure shadows that formed when the rock was being stretched. This took place some 15 million years ago in the Snake Range of eastern Nevada. This is an example of well-formed garnet crystals in a rock. If you zoom in on the picture, you can see the 12-sided crystal faces. Types of gemstones - gemstones guide A to Z Agate A unique variety of the quartz family, agate is relatively common and affordable. It has an average hardness of 6.5-7 on the Mohs scale.

Agate is known for the multicolored bands that might be likened to tiger stripes or tree rings. This beautiful feature is what makes agate such a popular gemstone. Some evidence shows that agate has been used by Human beings for up to 15,000 years. Today Agate is mined in the United States, Mexico, Germany, Italy, Brazil, China, India, Africa and a number of other countries. Alexandrite A variety of the mineral chrysoberyl, top quality alexandrite is very rare and very valuable. At 8.5 on Mohs scale, its hardness is considered to be relatively good. High quality alexandrite dramatically changes color from green in fluorescent light and daylight to purplish red in incandescent light. Discovered in Russia in 1830 and named after Czar Alexander II, it was soon adopted as the national stone of Russia. Its colors correspond to the Russian imperial colors. Other forms of alexandrite are mined in Brazil, Tanzania, Sri Lanka, India and Madagascar. alexandrite is also an alternative June birthstone in the United States. Amethyst A variety of the quartz family, amethyst is considered to be a common and affordable.

This colored stone has a hardness of 7 on Mohs scale, and varies in color from light lilac to deep purple. Amethyst is very sensitive to heat and sunlight. It may lose all of its color when exposed to strong UV rays for extended periods of time. Amethyst was believed by many cultures to possess various supernatural beneficial properties such as promoting piety and preventing alcohol intoxication. Mined in Brazil, Uruguay, Bolivia, Tanzania, Zambia, Namibia and small amounts can also be found in the United States. It is the February birthstone in the US. Aquamarine A variety of the beryl mineral, aquamarine is named for its sea-like color, which can range from pastel blue, to deep blue, to greenish or yellowish blue. Deep blue aquamarine stones are considered to be the most valuable of their kind. Aquamarine has a good hardness of 7.5-8 on the Mohs scale. It is frequently used in modern designs and is believed to be a lucky stone in several cultures. It is mined mainly in Brazil, Zambia, Mozambique, Angola, Nigeria and Madagascar, and is the March birthstone in the United States.

Citrine A member of the quartz family, citrine is typically more affordable than amethyst. This bright gemstone has a hardness of 7 on the Mohs scale. Its color ranges from bright yellow to honey and orange-brown. The name citrine comes from the French word for lemon, appropriately describing this colored stone's warm, inviting hue. It is mined in Brazil and Bolivia, where it is common and plentiful. Citrine is frequently exposed to heat enhancement in order to improve or modify its color. It is an alternative November birthstone in the United States. Coral Coral is an organic gemstone. Genuine, untreated coral is very rare and therefore very valuable. It is extremely delicate, its hardness measuring at approximately 3.5-4 on the Mohs scale. Coral is composed of calcium carbonate, which is secreted by small sea polyps in order to create their own natural protective habitat. Commercial coral is never harvested from protected reefs or banks, and harvesters have recently become more careful with their harvesting methods, dispatching professional divers to carefully collect coral branches so as to avoid damaging the sea organisms within. Most coral used in jewelry comes from Sicily or Sardinia.

Coral ranges in color from reds and oranges to whites and even blues. Emerald The emerald is a member of the beryl family. It is very rare and commands relatively high prices on the market. Because inclusion-free emeralds are extremely infrequent, the detection of inclusions minimally impacts the value of an emerald, if at all; only very severe and deep inclusions will reduce an emerald's value. The most highly-priced emeralds exhibit a bright grass-like green. Emeralds have a very good hardness of 7.5-8 on the Mohs scale. They are known worldwide for their exquisite green hue and have been embraced by mankind for over 4,000 years. Mentions of emeralds appear in the myths, legends and rituals of the Incas, the Egyptians, the Indian Moguls and the Ancient Greeks. They are believed by many cultures to have positive supernatural powers. Their green color can range from a very light yellowish green to a deep, dark, sometimes bluish tint. Currently, most emeralds are mined in Columbia, Brazil, Zambia, Zimbabwe, Afghanistan and Madagascar. The emerald is the May birthstone in the United States.

Garnet Garnet is the name of an entire family of stones that can be found in a wide spectrum of colors. The value of any garnet depends entirely on color, size and corresponding rarity. While deep red is the most common, affordable and traditional garnet color, garnets may range from green, orange, and yellow to earthier sepia hues; they come in almost every color, other than blue. Garnets have a good hardness of 7.5-8 on the Mohs scale. These gemstones have been valued by mankind for thousands of years and are mentioned most famously in the story of Noah's Ark. Garnets in common colors hail from India, Sri Lanka, Thailand, South Africa and the United States, while the more exotic garnet colors are mined in East Africa and Russia. The garnet is the January birthstone in the United States. Jade Jade is an umbrella term for two stones: jadeite and nephrite. Jadeite displays colors which include green, white, pink, red, black, brown, and violet. Nephrite typically displays mid to dark green or gray-green, but it can also be white, yellowish, or reddish. Only the finest jades have evenly distributed color.

Jade has been valued by both Eastern and Western countries for over 7,000 years. It is considered an especially precious symbol of royalty, compassion, goodness, beauty, modesty and more. Jades have an average hardness of 6.5-7 on the Mohs scale, but they are extremely tough. Because of this toughness, jades have been used by early civilizations to make knives, axes, tools and weaponry. They are well known for being an effective remedy for kidney ailments. The word jadeite originated from the Spanish 'piedra de ijada', and the word nephrite originated from the Latin' lapis nephriticus', both meaning 'loin stone'. Moonstone Moonstone is a member of the large feldspar family of minerals which includes about two-thirds of all stones on earth. It has a hardness of 6-6.5 on the Mohs scale, and exhibits a wide range of colors from green, brown, yellow, gray pink, rainbow, and colorless to very rare blues. High quality moonstones display a blueish luster. Generally thought to resemble moonshine, the token characteristic of the moonstone is its white shimmery glow.

History holds that the Romans and Hindus thought the stone was formed from actual pieces of moonlight, and many still believe that the future may be seen in its ethereal glimmer. The unique blue-glow of light that slides across the surface of the stone is caused by a type of light refraction called adularescence. Most moonstones come from Sri Lanka, but some are mined in India, Burma, Mexico and Madagascar. The moonstone is the June birthstone in Europe. Opal The word opal originates from the Greek 'opallos', meaning ' color change', referring to the color of the opal which seems to vary when tilted under light. This phenomenon occurs due to an internal diffraction of light which disperses a spectrum of iridescent colors. The opal family is well known for its special rainbow color play, and is available in an almost infinite array of hues including black, white, colorless, yellow, reddish, green, blue and multi-colored. The opal has an average hardness of 5.5-6 on the Mohs Scale. A myriad of superstitious legends exist regarding the origin of opals and the supernatural powers that these stones may possess.

The main origin of the opal is Australia, with Mexico and the US serving as its secondary sources. Opal is the October birthstone in the United States. Pearl The most valuable of all organic gemstones, pearls are created when an oyster senses an irritant within its soft shelled mouth and then coats it with layers of nacre. Today, almost all pearls on the market are cultured by artificially introducing a small bead or shell into the mouth of an oyster. The majority of pearls are cultured in Japan, but many are harvested in China and the South Pacific. Pearls range in size, shape and color: some are large, round and white while others are small, amorphous, and black. Pearls have always been considered classic gemstones, symbolic of beauty and dignity. The pearl is the zodiac gemstone for Cancer. Learn more about pearl types and characteristics in our Pearl Education pages. Peridot A member of the olivine family, peridot comes in a variety of shades of green. The signature lime-green peridot is a characteristic of the mineral itself, rather than that of a foreign element. Peridot is one of the sole gemstones that can be found in only one color.

It has a hardness of 6.5-7 on the Mohs scale. It is believed by some that peridot enhances the effectiveness of any medicine. According to others, peridot protects against nightmares. An indigenous Hawaiian myth suggests that a peridot stone is a tear of Pele, the Hawaiian fire and volcano goddess. Most peridot is mined in Arizona; other sources being China, Burma, and Pakistan. Peridot is the August birthstone in the United States. Ruby Ruby is the red manifestation of corundum; all other colors of corundum are referred to as sapphire. Due to its durability, brilliance and bewitching red color, it has for thousands of years been considered to be one of the most valuable gemstones. Larger rubies, being rarer, command the highest prices. This precious gemstone has a very good hardness of 9 on the Mohs scale. Owing to its red color, the ruby is commonly associated with passion, love, power, warmth, blood, and fire. Rubies have been worn by warriors to give them courage, by kings to give them power, and have been gifted as an expression of undying love.

The highest quality rubies exhibit a deep vivid red or purplish red. The ruby is the July birthstone in the United States. Sapphire Sapphire is a member of the corundum family. Sapphires most commonly occur in blue, and vivid, pure, deep blues are the most valuable. For thousands of years, sapphire has been associated solely with the color blue, its name originating from the Greek word 'sappheiros', meaning blue. However, sapphires can be found in every color besides red, as red sapphires are called rubies. Throughout the course of history, this gem has been worn as a protective amulet, as a symbol of harmony, loyalty and friendship, and as a romantic token. The stone has a very good hardness of 9 on the Mohs scale. Sri Lanka is the biggest producer of sapphires, but they are also mined in Kenya, Burma, Tanzania, Kashmir, Madagascar, Thailand, Vietnam, Cambodia, Laos, Australia, and the United States. The sapphire is the September birthstone in the United States.

Tanzanite A member of the zoisite family of minerals, tanzanite is found only in shades of blue or purple, the most popular being a violet-blue. While tanzanite is typically heat treated to enhance its blue color, it is naturally trichroic, meaning that it displays three different colors (blue, purple and bronze) when viewed from different angles. Tanzanite exhibits a hardness of 6.5-7 on the Mohs scale. It gets its name from the country of Tanzania, the only place in the world where it is found. Tanzanite was discovered as recently as 1967, and was christened by colored stone experts to be "the gemstone of the 20th century." Owing to its fast growing popularity, the American Gem Trade Association added it as an alternative December birthstone in the United States in 2002. Topaz Topaz is one of the most common gemstones worldwide. It has a very good hardness of 8 on the Mohs scale. Topaz comes in a rainbow of colors, the most valuable of which are the red, pink and orange stones which are mined in Brazil, Pakistan and Russia.

Colorless topaz is mined in Sri Lanka, Nigeria and China. Blue topaz is colorless in its rough form, and takes on its blue hue only after exposure to irradiation enhancement. It is quite sensitive to heat and sunlight, and may lose all of its color when exposed to strong UV rays for extended periods of time. Many cultures have claimed that topaz has mythical and magical strengthening powers. It is the traditional November birthstone and the alternative December birthstone in the United States. Tourmaline The word tourmaline was derived from the Sinhalese words 'tura mali', meaning 'mixed colored'. As its name indicates, tourmaline is found in a vast array of colors and color mixtures, more than any other gemstone in the world. For this reason, no two pieces of tourmaline are ever identical. Since many of its colors look similar to the colors of other gemstones, many tourmaline stones have been misidentified as rubies and sapphires. This colorful gem exhibits a good hardness of 7-7.5 on the Mohs scale. The rarest colors, which include copper and electric blue, are the most valuable.

Many magical powers have been attributed to tourmaline over the ages, including the power to enhance artistic creativity. Although Brazil is the most common source of tourmaline, the stone is also mined in Tanzania, Madagascar, Australia, Stri Lanka, the United States, and Russia. It is an alternative October birthstone in the United States. Turquoise A member of the copper family, turquoise is one of the oldest gemstones known to man, having been treasured by countless ancient civilizations across the globe. It is thought to have originated in Iran, where many Persians wore turquoise on their turbans to protect against the evil eye. Native Americans, Egyptians, Chinese and Tibetans also believe turquoise holds spiritual and protective powers. Turquoise is known for its light blue color, which can range from greenish-blue to sky blue, and at times exhibits yellow, black, gray, or even brown veining. This renowned gemstone exhibits an average hardness of 6 on the Mohs scale. As Iranian sources of turquoise have been nearly depleted over the centuries, the stone is now mined mainly in the southwestern United States, Mexico, Afghanistan, Israel and China. Turquoise is the December birthstone in the United States.

University of Minnesota’s Mineral Pages: Garnet ^ Top Did you know... The role garnet plays in your life in part depends on your interests and hobbies. For those with an interest in gems and jewelry, several commonly known gemstones are simply just different-colored varieties of garnet. In contrast, woodworkers, model enthusiasts, and home repair aficionados know garnet better as the ‘sand’ of sandpaper. Both uses are tied to garnet’s remarkable hardness. Description and Identifying Characteristics The word ‘garnet’ comes from the Latin word granatus, which means ‘seed-like,’ a reference to the common appearance of garnets as discrete small red rounded crystals that look like pomegranate seeds embedded in rock. The different garnet varieties comprise a group of minerals that all share a similar crystal structure, but whose chemical composition varies as different ions substitute for one another in that crystal structure. Most garnet crystals are actually mixtures of different garnet varieties rather than being composed solely of a single variety. As a result, there is little reason for non-specialists to worry about identifying individual garnet varieties. Although red garnets are the most common variety, garnets occur in nearly every color except for blue.

This variability in color results from the garnet crystals’ transparent to translucent nature, which allows minor impurities to greatly affect its appearance. Despite their variable appearance, garnets are usually easy to identify by their hardness, crystal habit and occurrence in metamorphic rock. Garnets usually form at high temperature and pressure, so they typically occur in their crystal form as rounded dodecahedrons (twelve-sided) or twenty-four sided trapezohedrons. Iron can substitute relatively easily for either magnesium or manganese in the garnet structure, but calcium is a larger ion and does not substitute as freely for iron, magnesium or manganese. As a result, the garnet group can be subdivided into two series of minerals – an aluminum silicate series in which Fe+2 Mg+2 and Mn+2 freely substitute for one another and a calcium silicate series in which Cr+3, Al+3 and Fe+3 substitute for one another. Natural garnets are almost always a combination of these end-members, rather than being a pure sample of one composition. Almandine ^ Top In Our Earth: The Geologic Importance of Garnet Garnets occur in some igneous rocks and pegmatites, but are more typical of high-grade metamorphic rocks.

Although identifying individual varieties of garnet is not important to a non-specialist, geologists use these different varieties as a way to gauge a rock’s metamorphic grade (the degree to which it has been altered), as the different garnets’ formation and composition reflects the temperature and pressure conditions their host rock endured. Hence garnets tend to record the geologic history of their host rock. Almandine, the iron-rich garnet variety, commonly forms from regional metamorphism of clay sediments and is the most common garnet in schists and gneisses. It also occurs in silica-rich igneous rocks, such as granite, rhyolite, or associated pegmatites. Pyrope, the magnesium-rich variety is more common in mafic igneous rocks and metamorphosed mafic igneous rocks, while the calcium-rich garnets, Grossular and Andradite, are commonly found in metamorphosed carbonate rocks. Spessartine is found in granite pegmatites and metamorphosed manganese-rich rocks, while Uvarovite is the rarest garnet variety, only occurring as crusts or seams in some chromium deposits.

As garnets are chemically and physically resistant they often survive the erosion of metamorphic rocks, becoming loose garnet grains. These garnet sands can be concentrated by wave and current action into ‘heavy’ mineral sand deposits. In most metamorphic rocks, garnets are typically associated with the mica minerals and other metamorphic minerals such as staurolite, kyanite, and sillimanite. Calcium-rich garnet varieties usually form in metamorphosed carbonate rocks where they may be found with calcite, wollastonite, or metallic ore deposits. Garnet grains in sedimentary sandstones usually occur with other heavy mineral grains or resistant minerals such as quartz. ^ Top In Our Society: The Economic Importance of Garnet Garnets have been used as gemstones for thousands of years, and with other red gems were often collectively known as carbuncles. Garnets’ color, hardness, and transparency make them attractive stones for use in jewelry, but they are generally too common to be prized as high-quality gems. Presently, garnet’s main economic value derives from its hardness and lack of cleavage, which makes it an excellent abrasive.

As an abrasive, garnet is primarily used as a loose-grain abrasive in air blasting or water jet cutting. In sand blasting operations, garnet sand is a safer alternative than the more traditional silica (quartz) sand because of the greater health risks of inhaling airborne silica dust. Fine garnet dust is used in the detailed finishing and polishing of optical lens, plate glass, and semiconductor materials. Garnet grains may also be affixed to materials as coated abrasives, and if you work with wood, you almost certainly have purchased sandpaper made of garnet grains. Because garnet is chemically stable, it is also used as a filtering medium for water purification systems or wastewater treatment plants. Some southwestern U.S. Indian tribes were responsible for one of the most unusual historical applications of garnet, when the circular shape, hardness, and blood-red color of garnet crystals, combined with a lack of local lead sources, led to their use as bullets. A similar use was also reported on the opposite side of the world during a 1892 rebellion against British troops in India.

Garnet’s common red color made a natural association with blood, and many cultures have used ground-up garnet for medicine’s associated with heart and blood diseases or as pendants or jewelry given in token of love or fidelity. Its glassy luster and transparent to translucent nature also led to folklore of garnet being used as a mystical light source, to lead the dead into the next realm or to light Noah’s way in his Ark. Garnet: The mineral Garnet information and pictures USES The Garnets are important minerals, and are primarily known for their gemstone uses. The transparent varieties are used in all forms of jewelry, with the most extensively used color being dark red. Other Garnet forms such as the reddish-orange Spessartine , yellow Grossular , and the green Tsavorite and Demantoid also make fine gemstones. See the gemstone section on Garnet for more detailed information, as well as the individual Garnet gemstone variety pages on Almandine , Pyrope , Rhodolite , Spessartite , Grossular , Tsavorite , Andradite , and Uvarovite for more detailed gemstone information on each Garnet gemstone form.

Garnets with a high hardness are used as an abrasive, and can be made into sandpaper known as Garnet paper. Well formed crystals and interesting aggregates very popular among mineral collectors. Garnet Quality Factors Garnet Quality Factors Garnet comes in as wide a variety of sizes and shapes as it does colors. Garnets are a group that includes a number of different minerals, so appearance can vary widely. The first thing a buyer of garnets needs to be aware of is the wide variety of garnet types. At first, the sheer number of garnet varieties can seem bewildering. It helps to think of the different types of garnets in terms of color. Color Pyrope and almandine range in color from purple to orangy red. Spessartine is found in a variety of orange colors, while andradite comes in yellow and yellowish green. Grossular has perhaps the widest color range of any garnet species, from colorless through yellow to reddish orange and orangy red, to a strong, vibrant green. These vibrant spessartine garnets are from the US state of Virginia, another important historical source for collectors.

- Gift of John Bradshaw This tsavorite garnet has an appealing green color and is a 68.82-carat gem. - Courtesy New Era Gems This 3.20-carat demantoid garnet’s vivid green hue is exceptionally beautiful. In fact, it’s close to the top color for this variety. The gem is mounted in a platinum ring with diamond accents. - Courtesy A Touch of Color Gemologists and colored stone dealers further subdivide some garnet species into varieties depending on color. For example, demantoid is a brilliant green variety of andradite that’s highly prized by collectors. Both tsavorite and hessonite are varieties of grossular. Tsavorites are green, while hessonite ranges from orange and orangy red to brownish red. Rhodolite is a purplish red variety. Rhodolite is the purplish variety of pyrope-almandine garnet. It can be spectacular, like this 8.72-carat gem. Clarity Typical garnet clarity depends on garnet type. For example, the red garnets almandine, pyrope, and rhodolite typically do not have eye-visible inclusions.

Some of the orange garnets, like spessartine and hessonite, often have eye-visible inclusions. Hessonite garnet often has a turbulent inner appearance called the roiled affect. - © GIA & Tino Hammid, courtesy Gordon Bleck Demantoid might have eye-visible inclusions called horsetails that can raise its value. Grossular is typically translucent, making it popular for cabochons, beads, and carvings. Cut Many garnets are cut into standard shapes and standard sizes to allow easy setting into jewelry. This is especially true of many red garnets. Expensive garnets like fine-quality tsavorite are cut into shapes and cutting styles that allow more of the weight to be retained from the rough. Garnets come in a variety of shapes and cutting styles. Demantoid is often cut to exact proportions that allow the best possible display of its fire. Garnets are also popular for designer cuts and carvings. Red garnets are classic materials for cutting into cabochons and beads. They are commonly found to have high clarity and to be very transparent. Carat Weight Garnets can be found in all sizes and weights.

Some garnets, like demantoid and tsavorite, are more commonly found in small sizes, so their value goes up significantly with size. Other garnets, like almandine, are far more common in larger sizes so there’s no dramatic rise in value as size increases. Learn More About Garnet Explore garnet history, research, quality factors, and more in the GIA Gem Encyclopedia.

Question: Garnet comes in many colours but what is the commonest
Answer: Red